Forest physiography; physiography of the United States and principles of soils in relation to forestry . the southward-flowing streamshave developed valleys in the plateau-like summit where the beds arenearly horizontal and where the conditions are therefore most favorablefor glacial plucking and sapping and for the development of broad flat-bottomed cirques. The northward-flowing glaciers worked upon steeplyinclined strata and were resisted by every hard stratum in the sectioninstead of a single hard stratum; hence they were but little assisted bysapping, for the soft beds whose removal gave
Forest physiography; physiography of the United States and principles of soils in relation to forestry . the southward-flowing streamshave developed valleys in the plateau-like summit where the beds arenearly horizontal and where the conditions are therefore most favorablefor glacial plucking and sapping and for the development of broad flat-bottomed cirques. The northward-flowing glaciers worked upon steeplyinclined strata and were resisted by every hard stratum in the sectioninstead of a single hard stratum; hence they were but little assisted bysapping, for the soft beds whose removal gave rise to the sapping of theharder beds above them soon dipped down beneath the plane of effectiveaction. The result was not only a greater amount of work to be per-formed by the northward-flowing streams but also a restriction of thefields of nourishment which correspondingly decreased the intensity ofglaciation. 1 S. F. Emmons, Science, n. s., vol. 6, 1897, p. 131 et al. 2 W. W. Atwood, Glaciation of the Uinta and Wasatch Mountains, Prof. Paper U. S. No. 61, 1910. 348 FOREST PHYSIOGRAPHY. ROCKY MOUNTAINS. II 349 FOREST GROWTH In the higher portions of the range the forest growth is extremelyscanty, but in the lower valley basins there is a heavy growth of co-niferous forest. The upper limit of forest growth is about ii,ooo feet,the lower limit on the southern slopes is beyond the base of the rangein the Uinta Valley and is less than 7000 feet, while on the northernslopes it is 9000 feet owing to differences of relief and to correspondingdifferences of exposure. The prevailing species are white pine, yellowpine, Engelmann spruce and Douglas spruce, besides species of lesserimportance. The view from one of the mountain lalces, with its deep-green water and fringe of meadow-land, set in the somber frame of pine forests, the whole enclosed by high walls of reddish-purple rock, whose horizontal bedding gives almost the appearance of a pile of cyclopeanmasonry, forms a pic
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectforestsandforestry
